Active photovoltaic string arc fault detection method and system

The invention provides an active photovoltaic string arc fault detection method and system. The method comprises steps of an active signal injection step, actively generating a high-frequency signal,and actively outputting the high-frequency signal at a photovoltaic string side; a current signal acquisition step, measuring and recording a current signal on a direct current bus on the photovoltaicstring side, and acquiring the current signal information on the direct current bus on the photovoltaic string side; and an arc fault judgment step, carrying out wavelet transformation machining according to the current signal information on the direct current bus on the side of the photovoltaic string side, analyzing signal characteristics after wavelet transformation machining, comparing the signal characteristics after wavelet transformation machining with input high-frequency signals, determining whether the photovoltaic string has an arc fault or not, and obtaining the arc fault detection result information of th